sql多查询

jjhzyzn0 于 2021-06-17 发布在 Mysql

关注(0)|答案(1)|浏览(304)

我有这种情况：

select AVG(t_vote.rating) as AVG_1 from t_vote  
INNER JOIN t_question.c_question = t_vote.c_question 
where t_question.aspect_code = 'A';

select AVG(t_vote.rating) as AVG_2 from t_vote  
INNER JOIN t_question.c_question = t_vote.c_question 
where t_question.aspect_code = 'B';

select AVG(t_vote.rating) as AVG_3 from t_vote  
INNER JOIN t_question.c_question = t_vote.c_question 
where t_question.aspect_code = 'C';

有没有可能在一个查询中用3个不同的where子句得到这3个不同的值？
这是我的table结构，如果我弄错了table，请纠正我
我把这个表作为一个例子，但我的表实际上看起来像这个表的例子

mysql

来源：https://stackoverflow.com/questions/53551099/sql-multiple-query

1条答案

按热度按时间

shstlldc1#

可以使用条件聚合：

SELECT 
  CASE WHEN t_question.aspect_code = 'A' THEN AVG(t_vote.rating) END AS AVG_1,
  CASE WHEN t_question.aspect_code = 'B' THEN AVG(t_vote.rating) END AS AVG_2, 
  CASE WHEN t_question.aspect_code = 'C' THEN AVG(t_vote.rating) END AS AVG_3 
FROM t_vote 
JOIN t_question 
  ON t_question.c_question = t_vote.c_question AND 
     t_question.aspect_code IN ('A', 'B', 'C');

赞(0）回复(0）举报 2021-06-18

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sql多查询

1条答案

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